Short and not so sweet today on sea level rise. It’s happening. It’s been happening. And we all know it is going to get worse. I’ve referenced it elsewhere in writing about floods and melting ice sheets, but for those who are interested in swimming a little deeper into the topic, Climate Central released not so long ago a Risk Zone Map that shows coastal flood risk globally, while the First Street Foundation released their Flood Factor map that allows users to search US flood risk by address for more or less every structure in the country. I recommend you play around with both.
Here’s some of what AR5 has to say about sea level rise:
Today’s post will address, in a simple (so highly reductive) fashion, a complex topic – namely the reduction in dissolved oxygen content in Earth’s oceans. Ongoing ocean acidification was addressed in a previous post on planetary boundaries, and I suspect most readers will have come across the statistic that, to date, oceans have taken up ~90% of the additional heat that has been trapped within the bounds of Earth’s atmosphere since the onset of anthropogenic global heating. The oceans are getting both more acidic (though, for now, they remain mildly basic) and hotter. As the EPA (still a thing, sort of) puts it, an “inverse relationship […] exists between dissolved oxygen and temperature. As the temperature of the water increases, dissolved oxygen levels decrease.” So as the oceans warm, their oxygen content decreases. This poses some clear and, on their face, relatively obvious threats to living beings in the oceans and (on top of warming, acidification, changes in currents and major climate patterns, loss of sea ice, etc.) the stability of marine ecosystems.
In brief, here’s what AR5 includes on the matter:
For readers interested in going a little deeper (pun acknowledged) on a related topic, the June issue of Nature Climate Change had a good piece on the risk that, even under an ambitious mitigation pathway, deep ocean waters are likely to warm disproportionately over the remainder of the 21st century owing to heating that is already locked in.
Postscript: At my mom’s request/suggestion, I may start including an action item/potential solution in each post. These are “Primers” are meant, not to engender despair, but to provide a foundation of knowledge for action and to reinforce the urgency of taking coordinated global climate action at scale.
In the spirit of economy (of words, not money), today’s post centers the cryosphere in its totality. The cryosphere, put simply, is the part of the Earth that is covered by frozen water (either in the form of ice, snow, or permafrost/frozen ground) at any given moment. Already, in the above-linked post on Arctic amplification, mention has been made of the dramatic loss of sea ice in recent decades, but glaciers, ice caps, the two extant ice sheets (of Greenland and Antarctica), and snowfall are all now in sharp decline. Obviously, the most sensational threat posed by loss of these cryospheric features of the now bygone Holocene is that of sea level rise: Were the Greenland Ice Sheet to melt entirely, global mean sea level (GSML) would rise ~6 meters or 20 feet; were the Antarctic Ice Sheet to melt entirely, GSML would rise ~60 meters or 200 feet. So if they were both to melt, that would amount to 220 feet of sea level rise (for people in the US who are accustomed to thinking in our non-standard standard units). That’s unlikely to happen anytime soon, though multiple feet by the end of this century looks like almost a certainty at this point, and with Indonesia moving its capital out of Jakarta, sunny-day flooding in Miami now the norm, and a surprising number of the world’s key cities (their positions very often a function of colonial trade networks and the garrisoning of the globe by the major imperialist powers over the last ~500 years) starkly menaced by rising tides, it’s understandable that increases in GSML are a special area of focus and concern; however, just as threatening for human populations and societies is the risk that the disappearance of glaciers and the shift in precipitation from snow to rain will radically alter hydrology with devastating impacts on agriculture and communities that depend on snow- and ice-fed river flows.
I’m putting today’s AR5 excerpt at the bottom (because it’s a doozy) in case people want to simply ignore it without missing anything below, but for readers especially interested in issues related to snow and ice, I can happily/sadly recommend The End of Ice from the courageous war-turned-climate reporter, Dahr Jamail.
As for the IPCC, here’s some of what AR5 had to say about unfolding and imminent changes to/driven by Earth’s cryosphere:
Today’s piece centers disruptions of the currents, circulations, oscillations, etc. in the ocean and the atmosphere that underpin the Earth’s climate as we know it. I can’t (so won’t) pretend an in-depth understanding of the Atlantic Meridional Overturning Circulation (AMOC), the Pacific Decadal Oscillation (PDO), or any of the other interrelated climatic mega-phenomena that were foundational to the ~12,000 years of Holocene stability during which human civilization took shape. (In fact, from my reading of the latest journal articles, it seems that even oceanic and atmospheric scientists are still very much in the process of figuring out how the interactions between the Earth’s atmosphere and oceans work.) Sadly, it seems increasingly clear that these mega-phenomenon are now at risk of collapse or serious disruption under climate crisis. Predicting the impacts of such climatic transformations strikes me as next to impossible, but it is to such likely cataclysmic changes in the fundamental organization of Earth’s life-supporting systems that the term climate regime shift refers. The Holocoene has ended; we are now living through a climate regime shift; and a rational goal, in my view, is to strive to stabilize the planet’s climate in a new regime as favorable as possible to the continuation of organized human life on Earth.
One example of AR5’s measured, vaguely optimistic language regarding such matters follows:
I, for one, don’t take much heart from their prediction, as actual events continue to outstrip the worst of scientists’ climate prognostications, and, after all, ideally we would leave a planet that is inhabitable for humans even after this century…
Following on yesterday’s piece (about droughts and floods), Sidewalk Labs (a subsidiary of Alphabet, aka, Google, and an entity the politics of which can, at some level, be summed up by noting that it claims to be “reimagining cities to improve quality of life” and yet chose to site its headquarters in the Hudson Yards development the construction of which its Chairman and CEO, Dan Doctoroff – in his previous role as Michael Bloomberg’s Deputy Mayor for Economic Development – was instrumental in facilitating) has this interesting piece up about Kansas City’s efforts to manage (through green infrastructure and digital sensors) stormwater runoff. I can also happily recommend the new podcast, Kaalavastha – from our friends Radhika and Samyuktha who must be having success as this latest production of theirs is brought to us by the World Bank – which humanely interweaves social, political, scientific, and climatic threads in recounting the impact of and response to catastrophic flooding in recent years in the Indian state of Kerala.
Today’s post centers two types of extreme phenomena driven by anthropogenic changes in the global water cycle, droughts and floods. As AR5 puts it:
Basically, many dry regions stand to get drier, many wet regions stand to get wetter, and many land masses that already experience “extreme precipitation events” (see: wet microbursts, not a porn term) stand to experience “more intense and more frequent” such events than they have in the past. Recent catastrophic fire seasons in Australia and California have been tied to unusually hot and dry weather, while it seems like Houston hardly goes a year these days without a once-in-a-century storm. In New York City, our summer thunderstorms increasingly have the character of the above-mentioned microbursts, while on the other side of this colonized continent, the US Southwest is in the midst of its worst mega-drought in 500 years (here’s the relevant Science study), and, of course, the Gulf Coast was just hit by another record-setting storm (this one driving an “unsurvivable” storm surge). I’d proffer other examples, but I suspect you don’t need them.